The present invention relates to the illuminating or indicating devices which are intended especially but not exclusively for motor vehicles.
Such devices conventionally and schematically include a light source emitting light rays which are gathered by a reflector mirror which reflects them towards glazing for enclosing and protecting the illuminating or indicating device in order to form an illuminating or indicating light beam.
By juxtaposing several of these devices, it is thus possible conventionally to provide different light beams each complying with various sets of regulations, relating to their photometry and their spatial distribution.
The light sources used may consist of incandescent lamps, halogen lamps or discharge lamps, these various lamps possibly coexisting in a headlamp or a side lamp, each lamp being intended to fulfill a function, that is to say to form the light source at the origin of a beam possessing predetermined regulatory photometry and geometry.
It may be desirable to use several light sources in order to fulfill the same function, either in order to obtain a more intense beam by using several of the above-mentioned light sources, or to obtain a beam of intensity equal to that of a beam obtained with a single one of these light sources, but by using several, less powerful light sources.
The problem which the simultaneous use of several light sources in order to form a beam then poses lies in the fact that the individual contributions from each source have to add together exactly in order to form a resulting beam the photometry of which is in accordance with the regulations in force.
In order to form an overall light beam, for example, including a regulatory cut-off, such as a dipped light beam or a foglamp beam, it is necessary, on the one hand, for each individual light beam, that is to say each beam generated by a single light source, to feature such a cut-off, and, on the other hand, for all the individual cut-offs to superimpose exactly in order to constitute the cut-off of the overall light beam, which otherwise would be fuzzy, and thus not in accordance with the regulations.
A device is known, for example, from the document U.S. Pat. No. 5,084,804 including several light sources consisting of light-emitting diodes connected in series and each situated at the object focus of a parabolic reflector. Such a device can provide an indicating beam, but not an illuminating beam.
A device is also known from the document WO-97/48 134, including light-emitting diodes mounted on a common support, the diodes emitting light beams of complementary colours, for example amber and green/blue, in such a way that the superimposition of these beams produces a resultant beam of white colour. Coloured glazing can be arranged so as to confer a particular colour on the beam emerging from the device, which, here again, can provide an indicating beam, but not an illuminating beam.
An illuminating device is furthermore known from the document EP-A-0 158 330, including several identical aligned modules, each module comprising a light source and a reflector. A common glazing is arranged in front of all the modules, so as to provide for the spatial distribution of the beam resulting from the superimposition of the beams created by each module, in such a way as, for example, to obtain a main beam or a dipped beam. The individual modules can then be positioned with respect to one another and with respect to the glazing with extreme accuracy so as, for example, to obtain a dipped beam with sharp cut-off.
Finally, an illuminating device is known from the documents EP-A-0 949 449 and EP-A-1 008 801, including a single light source, arranged at the first focus common to several ellipsoidal portions arranged in a corolla. Each ellipsoid thus forms an image of this single source at its second focus, an optical system associated with each image forming a part of the overall resulting beam. Although using a single light source, the light rays originating from this source are shared into a certain number of individual beams, converging towards several secondary point sources, converging lenses forming, from these secondary point sources, different beams being superimposed so as to constitute a beam of predetermined photometry, for example a dipped beam, if appropriate screens are arranged at the secondary point sources. Under these conditions, the light sources, the reflectors, the screens and the lenses have to have precisely determined relative positions, which results in great complexity of assembly of this illuminating device, high cost and a lack of reliability due to the vibration to which it is subjected during its use on a vehicle.
The present invention lies in this context, and its purpose is to propose an illuminating or indicating device using several light sources in order to form a light beam in accordance with a predetermined set of regulations, the assembly of the sources and their positioning with respect to the other elements of the illuminating or indicating device cooperating to form this light beam being carried out in a simple and reliable way, the illuminating or indicating device thus designed being inexpensive.
Hence the object of the present invention is an illuminating or indicating device, including at least two light sources, each light source being associated with a first optical system.
According to the present invention, each first optical system, at finite distance, forms a real image of the light source, the images of the light sources being coincident at a common point constituting a secondary source, and a second optical system having an optical axis passing through the secondary source forms an illuminating or indicating beam from this secondary source.
According to other advantageous and non-limiting characteristics of the invention:
the first optical systems consist of converging lenses forming light sources from the coincident real images so as to form the secondary source;
the first optical systems consist of ellipsoids each having an object focus coincident with the light sources, the image foci of the ellipsoids all being coincident in order to form the secondary source;
the second optical system consists of a converging lens, the object focus of which is coincident with the secondary source and forming the illuminating or indicating beam;
the second optical system consists of a reflecting surface, possessing an object focus coincident with the secondary source and forming the illuminating or indicating beam;
the reflecting surface is convex;
the convex reflecting surface is a portion of a paraboloid;
deflecting glazing is arranged downstream of the second optical system in order to confer on the light beam emerging from the device a predetermined spatial distribution;
the convex reflecting surface includes at least one region able by itself to generate an illuminating or indicating beam with cut-off;
a screen is arranged perpendicularly to the optical axis of the second optical system;
the screen is movable between two positions, a first position in which it intercepts part of the light rays constituting the secondary source and a second position in which it lets through all the light rays originating from the secondary source;
the light sources are light-emitting diodes;
the light sources consist of the extremities of optical fibres or of light guides;
the light sources are lit up selectively.
Other objects, characteristics and advantages of the present invention will emerge clearly from the description which will now be given of an embodiment example given in a non-limiting way by reference to the attached drawings in which